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Hi

I try to reproduce the propagation of waves on top of a constant sea elevation. I prescribe the same time-varying wave at the open-boundaries of my domain. I have checked the wave interpolation in time done by LIMWAC, and my interpolation works fine according to my print-outs. However, when I have a look to my tomawac results with Blue Kenue, my waves parameters at boundaries oscillate, do not follow my prescribed values and cannot propagate properly over my domain.

Has anyone already experienced similar problem? Would you have an idea on what triggers these "oscillations"?

Please find attached my tomawac steering file, the prescribed wave parameters and the print-outs of my calculation. A plot of my wave height evolution at the north boundary is also attached.

Many Thanks
Claire

my fortran file with limwac

and print-out file.

I fail in attaching my steering file, so copy it here:

/

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/ TOMAWAC Version v6p3
/ 05 Mar 2014
/ validating wave model when hm0 is high
/using southBC for waves and wind
/

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/

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/ COMPUTATION / DISCRETIZATION OPTIONS
/

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DEBUGGER = 1

TIME STEP = 50 /seconds 10
NUMBER OF TIME STEP = 146 /2days /real 720
NUMBER OF DIRECTIONS = 36
NUMBER OF FREQUENCIES = 22
MINIMAL FREQUENCY = 0.025
FREQUENTIAL RATIO = 1.1615
/SPECTRUM TAIL FACTOR =
BOTTOM SMOOTHINGS = 0
INFINITE DEPTH = FALSE

PARALLEL PROCESSORS = 32

/

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/ GENERAL PARAMATERS
/

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TITLE = 'mesh_Z2_surg305122013BCSouth_surgeSL0'
WATER DENSITY = 1027
MINIMUM WATER DEPTH = 0.1
/AIR DENSITY = 1.225
/

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/ INITIAL CONDITIONS
/

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/INITIAL STILL WATER LEVEL = 0.63 / meters
INITIAL STILL WATER LEVEL = 3.3 / meters needed
/INITIAL STILL WATER LEVEL = 0
TYPE OF INITIAL DIRECTIONAL SPECTRUM = 6 /Jonswap
INITIAL ANGULAR DISTRIBUTION FUNCTION = 3 /model in cos^(25) - Mitsuyasu
INITIAL SIGNIFICANT WAVE HEIGHT = 0.74
INITIAL PEAK FREQUENCY = 0.16
INITIAL MAIN DIRECTION 1 = 211.33

/

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/ BOUNDARY CONDITIONS
/

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LIMIT SPECTRUM MODIFIED BY USER = NO / i.e. using limwac
/LIMIT SPECTRUM MODIFIED BY USER = YES
TYPE OF BOUNDARY DIRECTIONAL SPECTRUM = 6
BOUNDARY ANGULAR DISTRIBUTION FUNCTION = 3
BOUNDARY SIGNIFICANT WAVE HEIGHT = 0.74
BOUNDARY MAIN DIRECTION 1 = 211.33
BOUNDARY PEAK FREQUENCY = 0.16

/

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/ SOURCE TERMS
/

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CONSIDERATION OF SOURCE TERMS = TRUE
CONSIDERATION OF A WIND = FALSE
/APPORTS DUS AU VENT
WIND GENERATION = 1
STATIONARY WIND = NO
/WIND GENERATION COEFFICIENT =
/WIND VELOCITY ALONG X = 19.7
/WIND VELOCITY ALONG Y = 3.5
CONSIDERATION OF A STATIONARY CURRENT = FALSE
CONSIDERATION OF TIDE = FALSE

WHITE CAPPING DISSIPATION = 1
TRIAD INTERACTIONS = 1 / LTA method
NON-LINEAR TRANSFERS BETWEEN FREQUENCIES = 1 / DIA method
DEPTH-INDUCED BREAKING DISSIPATION = 1 / Battjes and Janssen's model
DEPTH-INDUCED BREAKING 1 (BJ) COEFFICIENT GAMMA2 = 0.73 / gamma = maximum wave height / water depth
BOTTOM FRICTION DISSIPATION = 1 /note: only taken into account if INFINITE DEPTH = FALSE
/BOTTOM FRICTION COEFFICIENT = 0.025
WAVE GROWTH LIMITER = 2 /HERSBACH & JANSSEN 1999

/

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/ INPUT FILES
/

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GEOMETRY FILE = '../../mesh_Z2/geo_mesh_Z2.slf' / mesh file
BOUNDARY CONDITIONS FILE = '../../mesh_Z2/Z2_BC_waves.cli'
STEERING FILE = 'mesh_Z2_surge05122013BCSouth_surgeSL0.casw' / name of this file

FORMATTED FILE 1 = '../../wavewind_data_f5t7/wave_surge05122013_SouthBC_f5t7.txt'

WINDS FILE FORMAT = 4

/FORMATTED WINDS FILE='../../wavewind_data/wind_surge05122013_NorthBC_f4t7_wave_dir.txt'
/FORMATTED WINDS FILE='../../wavewind_data/wind_surge05122013_SouthBC_f5t7b.txt'

FORTRAN FILE='./fortran/limwac_noudon_int_new_bis_JohnDri_BCSouth.f'

/

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/ OUTPUT FILES
/

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2D RESULTS FILE = './results/mesh_Z2_surge05122013BCSouth_surgeSL0_test1460s.slf'

PERIOD FOR GRAPHIC PRINTOUTS = 1 / timestep interval for saving variables to file (ie = 1 save values at every timestep)

VARIABLES FOR 2D GRAPHIC PRINTOUTS = 'HM0,DMOY,TPR5,SPD,UWB,VX,VY,WD,ZF'

PERIOD FOR LISTING PRINTOUTS = 1 / timestep interval for outputting to the screen

Hello,

in your file wave_surge05122013_SouthBC_f5t7.txt, there is a very small value of the peak frequency fp=0.001 (at the second line). Your problem is probably not related to that, but could you check?

Regards,

Elodie

Hi

And thanks for that reply.
Sorry, I prescribed extreme parameters so as to check if the interpolation with LIMWAC is done correctly.
My problem is not related to that value, as I also get results with wiggles using other input parameters.

Regards
Claire

Hi Claire and Elodie,

I'm having the exact same problem that Claire described. I have not found a solution yet. I have checked my LIMWAC routine with printouts and everything seems fine. However, when I look at the results at the boundary, HM0 is oscillating.

I'm using a Jonswap type of spectre with no Wind and only offshore wave forcing the model.

Has anyone found a workaround for this ??

Thanks


Mathieu